Journal Pediatrics - Secondary Sexual Characteristics in Boys: Data From the Pediatric Research in Office Settings Network
Observed mean ages of beginning genital and pubic hair growth and early testicular volumes were 6 months to 2 years earlier than in past studies, depending on the characteristic and race/ethnicity. The causes and public health implications of this apparent shift in US boys to a lower age of onset for the development of secondary sexual characteristics in US boys needs further exploration. The earliest mean ages being 9.6 and 9.7 for Hispanic and African boys.
9-20 percent of boys could begin showing signs of puberty at the age of six
10 to 23 percent of girls show signs of puberty at the age of 7
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